The chemical synthesis of polyamide (peptide) nucleic acid (PNA) monomers 22-25 has been accomplished using Fmoc [N-(2-aminoethyl)glycine backbone], anisoyl (adenine), 4-tert-butylbenzoyl (cytosine) and isobutyryl/ diphenylcarbamoyl (guanine) protecting-group combinations, thus allowing oligomer synthesis on both peptide and oligonucleotide synthesizers. An alternative method for the preparation of (N6-anisoyladenin-9-yl)acetic acid 7 is described using partial hydrolysis of a dianisoylated derivative. Different methods were studied for guanine alkylation including (a) Mitsunobu reaction; (b) low-temperature, sodium hydride- and (c) N, N-diisopropylethylaminemediated alkylation reactions to give preferentially N9-substituted derivatives. Empirical rules are proposed for differentiating N9/N7-substituted guanines based on their 13C NMR chemical-shift differences.
|Number of pages||8|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|Publication status||Published - Jan 1 2000|
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